The nylon-resin sideplates are densely packed with long-glass fibers for a compact block with a high strength-to-weight ratio. Sheaves spin on high-load ball bearings with fitted races for low-friction operation. Ball bearings, sheave, and sideplates are UV-stabilized with carbon black for maximum protection.

Use 40 mm Carbo for jib and mainsheet systems on high-performance dinghies and for loaded control lines on small keelboats.